February 19, 2025
SURABAYA – The Nusantara Freshwater Fish Lovers Community (Kopipa) has called on the East Java administration to take stronger measures to protect the Brantas River, one of the province’s longest rivers, as severe pollution has caused the extinction of at least half of the fish species in the river.
On Monday, dozens of Kopipa activists protested by floating replicas of the locally extinct Hampala barb fish down the Surabaya section of the Kalimas River, a tributary of the Brantas.
Activist coordinator Jofan Ahmad said the Brantas River, a nationally strategic waterway, was now in a critical state.
“Insufficient government oversight of industrial waste, plastic pollution and riverside settlements has severely threatened the survival of the Brantas River’s native fish species,” he told The Jakarta Post on Monday.
Kurnia Rahmawati, a fish and culture researcher from Ecological Observation and Wetland Conservation (Ecoton), said a study conducted by the organization last year found only seven types of local fish currently inhabiting the downstream area of the Brantas River. Ten years ago, Ecoton researchers had documented 13 species of local fish in the same area.
The local fish species that have disappeared include the Schilbeid catfish (Laides longibarbis), bronze featherback (Notopterus notopterus), hampala barb (Hampala macrolepidota), cyprinid fish (Osteochilus hasseltii) and ray-finned fish (Macrognathus aculeatus).
“Indonesia is known as the second-largest fish producer in the world after China, but unfortunately, it is also one of the countries experiencing the second-largest rate of freshwater fish extinction, following the Philippines,” Kurnia said.
“This poses a significant threat to society, as freshwater fish are a vital source of protein for many communities,” she added.
In their study, Ecoton researchers also discovered a significant imbalance in the sex ratio of fish in the Brantas River, with 32 percent male and 68 percent female. This disparity suggests potential hormonal disruption in fish due to exposure to industrial and domestic waste.
Industrial and domestic waste contains endocrine-disrupting chemicals, which can cause intersex conditions in fish and reduce their reproductive performance by up to 76 percent.
According to Ecoton, there are several industries along the Brantas River that potentially contribute to its pollution, including 12 paper mills, 14 sugar factories, 4 flavoring plants, 20 recycling facilities and 5 feed mills.
Ecoton said pollution in the Brantas River not only threatened the fish population but also impacted 17 million residents across 17 cities and regencies who depended on the river, which stretches over 320 kilometers.
Ecoton and Kopipa have called on the East Java administration to install CCTV cameras and water quality monitoring devices at every industrial waste outlet along the Brantas River, allowing for real-time, public access to the data.
They also urged authorities to establish a task force to oversee and regulate liquid waste disposal in East Java and to initiate a river restoration program aimed at rehabilitating the river’s fish habitats.
“The government must take immediate action. Pollution in the Brantas River directly impacts food security and the well-being of local communities. If left unchecked, not only will fish face extinction but the livelihoods of thousands of fishermen and farmers will also be at risk,” said Zulfikar, a member of Kopipa.
The 2024 report from the Environment and Forestry Ministry highlights that 60 percent of rivers in Indonesia are severely polluted.
This pollution comes from industrial and domestic waste that harms fish and river ecosystems, the construction of dams that block fish migration and disrupt downstream environments, land use changes that convert natural areas into industrial and residential zones and the introduction of non-native fish species that threaten local species through competition and predation.